At present, beverages, such as water and colas, liquors, or liquid-type food, are contained in various kinds of containers. Examples of such liquid containers are paper bottles, PET bottles, glass bottles, and metal bottles (aluminum cans).
Of these containers, the PET bottle is the most popular liquid container thanks to its many advantages, such as that it can contain contents for a relatively long time, i.e. contents in the PET bottle barely decay after a long time of storage because gas transmittance of the PET bottle is very low compared with other kinds of containers, it hardly breaks when it is dropped in a state in which it is filled with contents, it does not produce broken pieces even when it is ruptured, and it is convenient to carry and keep the PET bottle because the PET bottle is lighter than a glass bottle.
The known PET bottle having the above advantages is generally composed of a neck which has an opening at an end and threads on an outer surface thereof for sealing when the neck is combined with a cover, and a body extending from the neck and containing contents therein. The body may be of various sizes and forms according to the type of contents.
There are ways of discharging the contents of the PET bottle. For example, when a user tilts the PET bottle to pour the contents into a vessel, such as a cup, or to directly drink the contents from the PET bottle, the contents are discharged from the PET bottle.
In such a case, there is a possibility that the contents contained in the body of the PET bottle are not smoothly discharged but are abruptly discharged at excessive pressure, so that the contents are likely to gush out of the PET bottle and to splatter on a user's clothes or the surrounding area.
In particular, when the user directly drinks the contents from the bottle, the user may choke or his or her clothes or body may get splashed.
Further, since the bottles have large volumes even when they are empty, it is difficult to deal with the empty bottles or it is required to install additional equipment in households to reduce the volume of the empty bottles.